Various electromechanical parking brake systems consisting of at least one brake mechanism unit and at least one control device are known from the prior art, with the actuation, in other words the applying and releasing of the brake mechanism unit for braking the vehicle, being controlled respectively by way of the at least one control device, preferably by actuating the brake mechanism unit by way of an electromechanical control element. The electromechanical parking brake system is preferably controlled by way of a simple operating element, for example a pushbutton, rocker switch or the like provided in the interior of the vehicle.
Such electromechanical parking brake systems are also configured for the static and in individual instances also the dynamic braking of a vehicle. In the case of the usual static braking in particular it is necessary for safety reasons for the vehicle to be almost stationary or its speed to be below a predefined speed threshold; in other words the static braking function is only provided by the electromechanical parking brake system when the speed is below the predefined speed threshold. If the vehicle speed is above the predefined speed threshold when the operating element is actuated, it is possible in some instances for dynamic braking of the vehicle to take place by means of the electromechanical parking brake system.
For static braking, a static application of the electromechanical parking brake system or brake mechanism unit is brought about at a high application speed by means of a, for example on-off, actuation of the operating element. In the case of a brake mechanism unit configured as a drum brake unit in particular such fast application results in a sudden deceleration of the vehicle due to the self-reinforcing effect of the drum brake present even at relatively low vehicle speeds. As well as an uncomfortable drive sensation, safety-critical drive situations can also result from the rapid braking of the vehicle. The brake mechanism unit is also subject to greater wear, which reduces its service life.
Electromechanical parking brake systems known from the prior art therefore have a fixed speed threshold of for example 3 km/h and if this is exceeded, the electromechanical parking brake system will not provide a static braking function. Alternatively, when the above-mentioned speed threshold is exceeded, the electromechanical parking brake system can be configured for dynamic braking. The dynamic braking function here directly follows the actuation of the operating element; in other words actuation of the operating element produces a preferably proportional dynamic braking force, while the brake is released directly when the operating element is released.